Question

efectuati 2+4+6+......+50 va rog dau coroana

Answer 1

2+4+6+...+50
= 2(1+2+3+...25)
=2•(25•26/2)
=2•650/2
=650( se reduce 2 cu 2)

Answer 2

2+ 4+ 6+ ... + 50= 2(1+2+3+...+25) –> Gauss

[2(25•26)]:2= 26•25= 650